The present invention relates to a control for an internal-combustion engine (which will be hereinafter referred to as an “engine”).
In recent engines, as described in Japanese Patent Application Publication No. 2005-120990, mounting, on an engine, a mechanism that is capable of changing a lift amount and a phase of an intake valve and controlling the amount of intake air into the engine through the mechanism are proposed
On the other hand, as described in Japanese Patent Application Publication No. H10-073068, an absolute pressure of an intake manifold is generally used for controlling an engine.
The atmospheric pressure at high altitude is lower than the atmospheric pressure at low altitude. Such a lower atmospheric pressure may influence various controls for an engine. Especially, if a control that uses the absolute pressure of the intake manifold is performed at high altitude, such a control may decrease an exhaust gas pressure, internal EGR amount, and the like. As a result, variations may occur in the intake air amount, fuel injection amount, ignition timing and the like. In the engine where the mechanism as described above is mounted, various controls for the intake air amount, fuel injection amount, ignition timing and the like are performed taking the lift amount and phase into account. For an engine having such a mechanism, it is desirable that controls for the engine are performed considering whether the vehicle is at high altitude or not.
In a case where the above-described mechanism is mounted on an engine, the number of parameters to be used in various controls of the engine may increase. Further, computation load for calculating controlled variables may increase. Especially, if a mechanism that is capable of continuously changing a lift amount and a phase of an intake vale is mounted on an engine, the number of parameters and the computation load may significantly increase. Therefore, it is desirable that such increase of the number of parameters and the computation load can be suppressed in controls of the engine.